DEFINING A REFERENCE BUILDING ACCORDING TO LEED V4, TO ENABLE COMPARISON OF LCA ALTERNATIVES

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1 DEFINING A REFERENCE BUILDING ACCORDING TO LEED V4, TO ENABLE COMPARISON OF LCA ALTERNATIVES Anna Olsson & Anel Steko Master Thesis in Energy-efficient and Environmental Buildings Faculty of Engineering Lund University

2 Abstract In this thesis the possibility of defining a general reference building, or so-called Baseline Building representing Swedish multi-family dwellings is investigated. The scope of the research is limited to analyze the multi-family dwellings of 3-8 stories. If succeeded the results should represent a general Baseline Building according to the new LEED v4 credit, Building Life-Cycle Impact Reduction. The credit requires a whole building life-cycle assessment to be carried out in order to evaluate environmental effects cause by the building design. However difficulties occur when developing a Baseline Building since no reference point is known. This leads to uncertainties when trying to improve the building design, since the reference point contains major variations. A suggested Baseline Building was derived by analyzing five questions from surveys conducted on the Swedish building stock, during These questions considered the building shape, structural components, and manufacturing method of the structural component, façade material and roofing material. Through the statistical analysis it was concluded that the most common building shape consisted of two building shapes, Apartment Block and Building Block. The choice of structural element consisted of partly prefabricated concrete elements for both building shapes. Furthermore plaster was found to be the most common façade material and metal sheet the most common roofing material. Despite this, no general Baseline Building that covered all building elements was obtained through the statistical review, due to high variations in greenhouse gas emissions caused by different construction types. The results should instead be used as material suggestions for the building envelope and structural elements of a Baseline Building. The results from the investigation are intended to guide project teams in selecting appropriate materials in an early design stage regarding the Baseline Building design. As the final step sensitivity analysis were conducted by defining different construction and material types of a Baseline Building design and analyzed in a simplified LCA tool. From the LCA study we could conclude that the structural elements affected the LCA results the most. In conclusion the structural elements should be analyzed in early design phase through a what if scenarios to improve the LCA outcome.

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4 Acknowledgements This project has been performed within the master program Energy-efficient and Environmental Building Design (EEBD) at the Faculty of engineering, LTH, Lund University. We would like to take the opportunity to thank the persons that in different ways have contributed to this master thesis. First of all we would like to thank our supervisors at Skanska, Björn Berggren and Jeanette Sveder-Lundin, for their knowledge in the field of this thesis. Their guidance and feedback has been very helpful to finalize this thesis. We would also like to thank our supervisors Charlotte Retzner and Mikael Lantz and our examiner Dennis Johansson who gave us helpful input regarding this subject. Finally, a special thanks to our family and friends for their continuous support. Helsingborg, May 2015 Anna Olsson Anel Steko

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6 Definition list ASTM C272 ANSI ASHRAE Addenda Baseline Building BBR 22 Boverket DOE-2 E-waste Errata EnergyPlus EPD IES Multi-family dwellings PBF Proposed design Reference building American Society for Testing and Materials American National Standards Institute American Society of Heating, Refrigerating and Air- Conditioning Engineers Continuous maintenance of published standards regarding additional items Designed reference point when evaluating energy and LCA improvements. LEED v4 refers to a Baseline Building for when evaluating improvements The latest version of BBR, Swedish National Board of Housing, Building and Planning Energy analysis program for buildings Electronic waste, computers, printers, fax machines etc. Continuous maintenance of typographical errors, misprints, misspellings and grammatical errors to the published standard or guidelines Energy analysis program for buildings Environmental Product Declaration, document verifying the environmental performance of a product or service, based on LCA Illuminating Engineering Society Houses for more than one house hold Plan- och Byggförordning, translation: Planning and Building regulation Optimized building design based on results from Baseline Building Baseline Building

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8 Table of content 1 Introduction Background Purpose Scope and limitations Disposition of report Method 4 2 LEED General background Impact categories LEED categories Building Life-Cycle Impact Reduction (MR) Minimum Energy Performance (EA) Certification process Findings from LEED 22 3 Building standards ASHRAE General background Appendix G BBR General background Building envelope requirements, BBR Findings from Building standards 34 4 LCA General background The ISO series How to perform an LCA according to ISO 14040/ Findings from LCA 44 5 Development of a Baseline Building Analysis of the Swedish building stock Data collection Data process and analysis Starting point for baseline Starting point for building design Starting point for building components Analysis of LCA 52 6 Result Analysis of the Swedish building stock Starting point for Baseline Building Starting point for building design Starting point for building components Analysis of LCA LCA for different building components LCA for whole building 79 7 Discussion Conclusion References Appendix A. U-value calculation... 93

9 Appendix B. Fenestrations Appendix C. Architectural drawings Appendix D. LCA Building components

10 1 Introduction 1.1 Background The industrialization has not always been considered harmful to the environment. In the 1800s, it was desirable to have industry in the neighborhood where black smoke poured out from the chimney. In those days the factories were seen as the future and symbolized success. When the negative side effects were realized in the 1900s different strategies were developed in order to reduce the environmental impacts (Rydh et al., 2002). Today the construction industries have developed different methods to keep track of the environmental effects caused by buildings. One solution used by the construction industry is to incorporate green building program in the design process. One of these programs is the American, Leadership in Energy and Environmental Design (LEED), which was studied in this thesis. Today there are 196 LEED certified projects in Sweden compared to buildings in the United States. Out of all certified projects, residential multi-family buildings only account for a small portion, most of the LEED certified buildings are offices owned by corporates (U.S. Green Building Council, ). LEED certified buildings are designed to lower the operating costs and increase assets value, reduce waste sent to landfills and reduce the emissions of greenhouse gases etc. LEED was studied in this thesis since it recently released a new version, LEED v4, which includes a new credits regarding life-cycle assessment (LCA). This new credit in LEED was chosen for this thesis since it addresses a new field within the construction industry, a whole life-cycle assessment. The new credit Building Life-Cycle Impact Reduction encourages projects to make early design decisions in order to reduce the environmental impact (U.S. Green Building Council, 2013). The LCA credit introduces two models, a Baseline Building and a proposed building. Projects pursuing the credit are required to create a Baseline Building that is used as a reference point. The LCA credit is achieved by displaying relative reductions of emission outlets by investigating different design alternatives. Reductions are based on a Baseline Building design and Proposed Building design. Where s the Baseline Building is created to represent common building design including the structural element and building envelope. While the Proposed Building is improved through what if scenarios in the Baseline Building design, to display a reduction of emission outlets compared to the Baseline Building. According to interviewed LCA practitioners there exist difficulties when creating a Baseline Building. This is because of uncertainties in the choice of materials for the Baseline Building. LEED states that the Baseline Building should represent common material and construction choices in the development of a Baseline Building. However no recommendations are found in LEED v4, regarding appropriate 1

11 materials or constructions for the structural elements and building envelope. Because of this the relative emission reduction will vary significantly depending on how each project develops there Baseline Building. 1.2 Purpose This thesis investigates the possibility of creating a general reference building, or socalled Baseline Building, that fulfills both Swedish regulations and requirements found in LEED v4. The purpose is to evaluate the possibility of creating a common Baseline Building that represent all Swedish multi-family dwellings, which would act as a common reference point. This thesis will provide guidance for project teams in the early design phase, when creating their Baseline Building. This is presented in a step-by-step guidance in which material requirements, appropriate material choices, appropriate design measures etc. are discussed. The following main questions are investigated: How should a reference building be defined according to LEED v4? Is it possible to define a general reference building applicable to Swedish conditions? Which building components contribute the most to greenhouse gases (global warming potential, CO 2 -eqv.)? 1.3 Scope and limitations The scope of the thesis is limited to two different areas, first regarding the building model and its location, secondly limitations of the chosen LCA tool. Building model The building types chosen to analyze include newly constructed 3-8 story multifamily dwellings. The boundary is based on Swedish building regulations, PBF, which state specific requirements for different story heights. The lower limit is based on mandatory requirement for accessibility and usability found in PBF chapter 3, 4 : Building shall be accessible for people with reduced mobility and orientation capacity, access to elevator should be available except for residential building with two stories or lower. The upper limit is linked to the fire protection requirements intended for high-rise residential buildings (+8 stories). Residential buildings over eight stories contain higher requirements for accessibility to fire evacuation, found in BBR 5:321. These increase the building cost. The building location is set to represent one climate zone according to LEED v4 requirements. For this reason Malmö is chosen as building location. 2

12 Building dimension and design is gathered from conceptual building designs created by Skanska. The building materials is gathered through statistical analysis, which only includes data from LCA The LCA is limited to only include one impact category Global Warming Potential (GWP), greenhouse gases, as CO 2 -equivalents. This is due to limitations in the chosen datasets, which only include CO 2 -equivalents for global warming potential. 1.4 Disposition of report The report is divided into four parts, the three first parts, chapter 2, 3 and 4, are used for gathering necessary information regarding background, requirements and guidelines found in LEED, LCA, building regulations and standards. Each part is followed by results, which describes necessary information for modeling a Baseline Building. These results also answer the questions stated for each part. The fourth part, chapter 5, contains the process of creating a Baseline Building in compliance with the results found in the first three parts. In addition to the development of a Baseline Building, a sensitivity analysis regarding the effect of different design alternatives are investigated and their impacts on the emission outlet. Chapter 2 Chapter 2 investigates modifications made in the newest version of LEED v4 and describes requirements specified to model a Baseline Building. The findings from LEED describe the necessary requirements when pursuing the LCA credit Building Life-Cycle Impact Reduction in LEED v4. Questions to answer: What is needed to reach the credit Building Life-Cycle Impact Reduction for new constructions in LEED v4? Which requirements are mandatory to fulfill when designing a Baseline Building according to LEED v4? Chapter 3 The third chapter describes the American building energy efficiency code ASHRAE , and its connection to LEED v4. LEED v4 refers to specific requirements in ASHRAE when developing a Baseline Building design and Proposed Building design. The standard is mandatory to follow when pursuing the LCA credit Building Life-Cycle Impact Reduction in LEED v4. The findings from building standards present a comparison between the requirements found in ASHRAE and the Swedish building standard BBR 22. 3

13 Questions to answer: Which requirements are mandatory to follow when designing a Baseline Building according to LEED v4? Are there any similarities between ASHRAE and BBR 22? Chapter 4 Chapter 4 describes mandatory ISO standards to follow when conducting LCA for a Baseline Building and Proposed Building design. The LCA studies include specific requirements for method, structure and allowed datasets in LCA studies. Questions to answer: What should is included in ISO and ISO ? What is included in a cradle-to-grave LCA? Chapter 5 The fifth chapter uses the results from the previous chapters to develop a Baseline Building according to LEED v4. The fifth chapter includes the process for developing a Baseline Building. Analysis of statistical data regarding common material is presented, as well as a step-by-step process in developing a Baseline Building. Finally a LCA study is conducted for the Baseline Building design and proposed design measures to reduce the environmental impacts. Questions to answer: Which design measure is allowed to vary? What is the relative impact reduction caused by the proposed design measure? 1.5 Method As a first step of this report, see Figure 1, necessary information and requirements regarding how to develop a Baseline Building according to LEED v4 was studied. Requirements and information regarding the Baseline Building is stated in the reference guide of LEED v4. The complete LEED v4 reference guide was collected from USGBC website. 4

14 Literature study The Swedish building stock Starting point Baseline Building LCA of Baseline Building LEED ASHRAE ISO standards BBR SCB BETSI Material suppliers Skanska VSAA Wikells Sektionsfata Material suppliers Different materials Different constructions Different combinations Figure 1. Method description. From the study it was learned that requirements stated in appendix G of ASHRAE standard and various ISO standards were required. These were needed to fully understand the required documentation process when pursuing the LCA credit in LEED v4. The ASHRAE standard and its user manual were received at Skanska. To understand how the method for conducting an LCA has changed, a literature study of this was conducted, the literature was found at LUBsearch and in the library at Campus Helsingborg. The ISO standards were collected at Skanska and LTH. Since the Baseline Building is located in Sweden, Swedish building requirements should be fulfilled. For this reason the latest building standard, BBR 22 was studied. The building standard, BBR 22 was found at their website. Since none of the studied standards or manuals described a starting point for the Baseline Building, investigations where necessary to find common building materials and construction types. Statistical analysis was conducted on SCB survey results regarding material selection in multi-family dwellings, during Along with the SCB results, information derived from BETSI project was combined. The BETSI project included technical status of multi-family dwellings including U- values. These where needed to describe the performance level of the building envelope. In addition material and assembly information from material suppliers where used to fill out any necessary gaps. After the Swedish building stock was analyzed, common building materials and construction types used in multi-family dwellings was answered. The next step included to develop the Baseline Building according to the requirements stated in 5

15 LEED v4 and ASHRAE For this reason a building design was needed. Building dimensions where gathered from Skanska representing conceptual building designs. In addition each building component was assessed through Wikells section data to determine the amount of material for each construction. Construction types missing in Wikells was answered through contact with material suppliers. When the Baseline Building was designed, a sensitivity analysis was conducted to discover which materials had the highest emission outlet. The best environmental performance was assessed to a Proposed Building design which altered the material selection, construction type and building component combination. Requirements regarding allowed design alternations were followed from the specified requirements of LEED v4, ASHRAE standard and ISO standards. 6

16 2 LEED This chapter contains gathered information regarding the environmental certification system LEED. This part presents general background information, what is included in LEED and the LCA credit, Building Life-Cycle Impact Reduction. At the end of this part the results of this chapter is presented. 2.1 General background Leadership in Energy and Environmental Design (LEED) was developed by the U.S. Green Building Council (USGBC) to reduce the growing environmental problems caused by the construction industries, and to create more sustainable societies. The framework of the certification scheme is structured to assist identification, implementation and measuring of sustainable building designs. Including both buildings and whole neighborhoods in an early design stage. LEED certification scheme is a market driven, voluntary, consensus tool which serves as guidelines towards sustainable building designs. The aim is to promote conversion to a greener and more sustainable environment. Achieved by optimizing the use of natural resources, maximizing the positive and minimize the negative effects on the environment and human health at the same time promoting a high quality indoor environment. The framework, which guides users in their design process, consists of a set of achievable credits and mandatory prerequisites that promote sustainable building solutions. To achieve a LEED-certification projects must collect points through credits and at the same time comply with mandatory prerequisites (U.S. Green Building Council, 2013). The first LEED pilot version (LEED version 1.0) was developed in After extensive modifications LEED version 2.0 was first released in Since the first release LEED has been updated several times to include technical solutions, new markets and building types. LEED version 2.1 and 2.5 were released during 2002 and Since it first started LEED has grown and adapted with technical advances in the construction industry. Thus the certification system has contributed to awareness in climate changes and health effects caused by the building industry (U.S. Green Building Council, 2009). LEED is updated continuously, following the development in technology and practice made in the construction industry. During the update process members of the U.S. Green Building Council (USGBC), committees, and subcommittees review the new versions to ensure that LEED meets the need of the growing market sector (U.S. Green Building Council, 2013). 2.2 Impact categories LEED is defined by seven main goals. These goals and visions are divided by how they improve human health and environmental aspects into so-called Impact Categories. The goals and visions describe what LEED projects should accomplish: Reverse contribution to Global Climate Change Enhance Individual Human Health and Well-being 7

17 Protect and Restore Water Resources Protect, Enhance and Restore Biodiversity and Ecosystem Services Promote Sustainable and Regenerative Material Resources Cycles Build a Greener Economy Enhance Social Equity, Environmental Justice, and Community Quality of Life (Owens, 2013) LEED has established seven impact categories that contribute to the goals and visions by different weighting of the total points. LEED v4 introduced major changes to the impact categories, compared to previous version; to better correspond with LEEDs goals and visions. The allocation in LEED v4 is presented in Figure 2. What should LEED project accomplish? 5% 5% 10% 35% Climate Change Human Health Water Resources 10% Biodversity Green Economy 15% 20% Community Natural Resources Figure 2. Allocation of the Impact Categories in LEED v4. The approach is similar to the previous LEED 2009 version. All impact categories are weighted, where some categories are considered to have a larger importance and relevance to the construction industry. While other impact categories may be important for the environmental problems, but are less probable to be reduced by the construction industry. A larger percentage of the total points have been allocated to LEED v4 for the impact category Climate Change, compared to LEED 2009 (Owens et al., 2013). 2.3 LEED categories LEED has transformed throughout the years, where credits and prerequisites have been renewed, combined or altered. LEED version 2009 had five categories 8

18 containing mandatory prerequisites and optional credits existed in the rating system Building Design and Construction (BD+C) for New Construction. The LEED categories contain requirements when assessing credits and prerequisites to comply with to reach different levels of certifications. The categories from previous LEED 2009 and LEED v4 are compiled in Table 1. Table 1. Comparison between previous LEED version 2009 and LEED v4 LEED 2009 Points LEED v4 Points Base points - - Integrative Process (IP) Location & Transportation (LT) 16 Sustainable Sites (SS) 26 Sustainable Sites (SS) 10 Water Efficiency (WE) 10 Water Efficiency (WE) 11 Energy & Atmosphere (EA) 35 Energy & Atmosphere (EA) 33 Materials & Resources (MR) 14 Material & Resources (MR) 13 Indoor Environmental Quality (IEQ) 15 Indoor Environmental Quality (EQ) 16 Additional points Innovation in Design (ID) 6 Innovation (IN) 6 Regional Priority (RP) 4 Regional Priority (RP) 4 LEED v4 follows the same base point principle as in previous version, LEED 2009, with a maximum of 100 base points and 10 additional points for the categories Innovation in Design (ID) and Regional Priority (RP). In LEED v4 the distribution of points has been reallocated with regards to the new allocation of impact categories. In addition to the reallocation of points, new categories have been developed in LEED v4. The categories include now an Integrative Process (IP) and Location and Transportation (LT) (U.S. Green Building Council, 2013). The location and transport (LT) category contains transferred credits from previous LEED 2009 category Sustainable Sites (SS). Where s the Integrative process (IP) includes a new credit for new construction. The credit is intended to create synergize in early design decisions through interrelationships in the project team. (U.S. Green Building Council, 2014). A roadmap is shown in Figure 3, displaying modifications of prerequisites and credits between LEED 2009 and LEED v4. 9

19 LEED 2009 MRP1: Storage and Collection of Recyclables MRC1.1: Building Reuse - Maintain existing walls, floors and roof MRC1.2: Building Reuse - Maintain interior nonstructural elements MRC3: Material Reuse MRC4: Recycled Content MRC5: Regional Materials MRC6: Rapidly Renewable Materials MRC7: Certified Wood MRC2: Construction Waste Management LEED v4 Prerequisite: Storage and Collection of Recyclables Prerequisite: Construction and Demolition Waste Management Planning Credit: Building Life-Cycle Impact Reduction Credit: Building Product Disclosure and Optimization - Material Ingredients Credit: Building Product Disclosure and Optimization - Environmental Product Declarations Credit: Building Product Disclosure and Optimization - Sourcing of Raw Materials Credit: Construction and Demolition Waste Management Figure 3. Road map displaying changes made between LEED 2009 and LEED v4, in the Material and Resource category Prerequisites The prerequisite, storage and collection of recyclables from LEED 2009 have been transferred to LEED v4 with minor additions. The prerequisite now include additional materials for dedicated storage, where the project should choose two of the three materials. The new materials include: Batteries Mercury-containing lamps, and E-waste. LEED v4 include one new prerequisite, which is closely connected to the construction and waste management credit in LEED The new prerequisite 10

20 Construction and demolition waste management planning states that all projects shall include a construction waste management (CWM) plan. Credits The Building Life-Cycle Impact Reduction credit in LEED v4 includes major modifications. The credit is new and combines criteria from three credits in LEED 2009 into one credit in LEED v4, see Figure 3. The credit is intended to reduce embodied energy, reduce waste and reduce impacts associated with material extraction, processing, transport, maintenance and disposal. Criteria from MRC1.1 and MRC1.2 are combined into option 3, Building and Material Reuse, for the new credit Building Life-Cycle Impact Reduction. These state how walls, floors and interior nonstructural elements should be reused for achieving the credit through option 3. New to the criteria is the possibility to incorporate both structural and nonstructural elements The credit Building product disclosure and optimization - environmental product declarations combines criteria from MRC3, MRC4 and MRC5. Some materials that were excluded from the criteria in the past, have now been included in the new LEED v4 credit. Materials such as mechanical fixtures, fittings and rough-in materials that are considered nonmoving mechanical, electrical and plumbing (MEP) components, may now be included. The modifications include: MRC3: Materials reuse Materials that are reused are no longer required to be repurposed MRC4: Recycled content No changes is made to the requirements MRC5: Regional materials The 500 mile (805 km) radius have been decreased to 100 miles (160 km). The definition now includes the distribution and purchase location, which extends the scope to include all points of manufacture. The credit Building product disclosure and optimization - sourcing of raw materials have combined multiple criteria from previous LEED 2009 version. These include the criteria found in MRC6 and MRC7, which include minor changes from previous version. The modifications include: MRC6: Rapidly renewable materials Bio based materials are no longer defined by the harvest cycle of the raw materials. Instead the products must meet the Sustainable agriculture standard to count for this credit. MRC7: Certified wood No changes is made to the requirements. LEED v4 introduces a completely new credit, Building product disclosure and optimization - material ingredients. 11

21 As mentioned before, the CWM plan from MRC2 credit in LEED 2009 have transformed in a prerequisite. In addition to this, the credit has been transferred to LEED v4 credit Construction and demolition waste management. The credit includes the following modifications: The credit includes added compliance options for the total waste reduction per gross floor area Multiple material streams must now be diverted to earn the credit for diversion of waste (option 1) Alternate Daily Cover (ADC) is specifically excluded from diversion calculations. LEED 2009 allowed ADC to count for as diverted waste Waste-to-energy is now allowed to count as a diversion method as long the European Union s requirements for waste management are meet (U.S. Green Building Council, 2014) Building Life-Cycle Impact Reduction (MR) The Material and Resources (MR) credit, Building Life-Cycle Impact Reduction investigates the life-cycle of permanently installed materials. The environmental impacts caused by materials are assessed from a life-cycle perspective with a minimum requirement of cradle-to-grave perspective. When recycled materials are available, the life-cycle perspective could be extended to cover a cradle-to-cradle perspective. The intention is to offer a life-cycle approach to reduce the environmental impacts caused by the building materials and increase resource efficiency (U.S. Green Building Council, 2013). The intent of the credit is to encourage adaptive reuse and optimize the environmental performance of products and materials (U.S. Green Building Council, 2013). The credit requires a reduction of environmental impacts based on design decisions in an early design phase stage, preferable before selecting the structural and building envelope materials. The credit rewards points for different projects types, where options for reusing resources from existing buildings and by a making an in-going LCA. Since there are various ways of fulfilling this credit, there are four different options to choose from. Option 4, Whole-Building Life-Cycle assessment rewards projects three points when achieving 10 % reduction in three of six possible impact categories, presented in Table 2. The impact category Global Warming Potential is mandatory for all projects and was included in previous LEED However none of the impact categories are allowed to increase more than 5 % compared to Baseline Building. In addition to the three points, an extra point is awarded through the Innovation credit. The Innovation (IN) credit, option 1, rewards projects that achieve significant, measurable environmental performance using a strategy not addressed in the LEED green building rating system. This is achieved by displaying reduction in all six impact categories, instead of only three as LEED v4 requires. (U.S. Green Building Council, 2013). 12

22 Table 2. Impact categories assessed in "Building Life-Cycle Impact Reduction" Impact Categories Global warming potential (greenhouse gases), CO 2 -eqv. Depletion of the stratospheric ozone layer, in kg CFC-11 Acidification of land and water sources, in moles H+ or kg SO2 Eutrophication, in kg nitrogen or kg phosphate Formation of tropospheric ozone, in kg NOx or kg ethane Depletion of nonrenewable energy resources, in MJ Both the Baseline Building and Proposed Building design must fulfill functional equivalence. These include the following parameters to be equal in both designs: Be of comparable size Have the same function Have the same gross area Have the same orientation Have the same system boundary, a cradle-to-grave analysis. All life-cycle stages regarding the building structure and enclosure should be analyzed, according to the definition in ISO 21930, following sections A1 - A4, B1 - B7 and C1 - C4. Parameters that are not defined may be changed across the baseline and proposed building Have the same operating energy performance, which is defined in EA prerequisite Minimum Energy Performance Have the same service life at least 60 years, to include products maintenance and replacement cycle Use the same software tool and datasets when conducting a life-cycle assessment, chosen datasets must be compliant with ISO (U.S. Green Building Council, 2013) Step-by-step guidance for Building Life-Cycle Impact Reduction, option 4 The follow part presents a step-by-step guidance described in LEED v4. The guidance describes how option 4, whole building life-cycle assessment, for the credit Building Life-Cycle Impact Reduction should be carried out (U.S. Green Building Council, 2013). Step 1 Calculate existing building surface area and reuse existing building The scope of the LCA should be a cradle-to-grave assessment, from design to demolition. The LCA should follow the system boundaries A1-A4, B1-B-7 and C1-13

23 C4 according to ISO for the building structure and enclosure. This includes the product stage, construction process, use stage and end-of-life stage. Products The Baseline Building contains mandatory products to include when conducting an LCA. These products include structural elements and building envelope materials. The following building components should either be included, excluded or optional. Included: Footing and foundations Structural pillars, columns etc. Structural wall assembly (from cladding to interior finishes) Structural floors and ceilings (not including finishes) Roof assemblies Parking structures, exclude parking lots Stair constructions Excluded: Electrical and mechanical equipment and controls, plumbing fixtures, fire detection and alarm system fixtures, elevators and conveying systems Exclude excavation and other site development Optional: Interior nonstructural walls or finishes may be included, but earn no additional credit Step 2 Select appropriate tools and datasets for LCA assessment The choice of LCA tool and dataset should be carefully reviewed to ensure the most suitable option is chosen for the project. The choice of dataset will determine whether a LCA specialist is required or not. Tools/software and datasets must be: The LCA tool or software must be used for both the Baseline Building design and Proposed Building design. The dataset used in the tools/software must be compliant with ISO and relevant data sets for the project location must be selected The tool must be ensured to enable a whole building life-cycle assessment including the relevant impact categories 14

24 LCA tool selection When assessing the Building Life-Cycle Impact Reduction several LCA tools can be used. All LCA tools use imbedded datasets, based on LCA standards. The data is specific to the building location, material manufacturer and regional electricity production. Different LCA tools require different levels of knowledge, where limitations exist in the possibility of modifying or adding data. These are divided in two categories, one for non-lca-practitioners and one for LCA-practitioners. Design team LCA tools are simplified LCA tools and are intended for non-lca practitioners. These programs use simplified calculated methods where the LCA calculation runs in the background and do not allow users to modify or add data. Examples of these programs are: ATHENA Impact Estimator Envest 2 LCADesign LCA practitioner tools require a LCA specialist, which is familiar with calculating factors and choosing appropriate datasets. These tools/software allow more flexibility where the LCA is based on product-by-product assessment and require different methodologies for the products examined. The practitioner aggregates all products into a whole building life-cycle assessment. Examples of these programs are: SimaPro GaBi Step 3 Create model Baseline Building Identify the baseline early in the design process Once the project scope is determined, all building components of the building envelope should be defined. These include exterior walls, roof, joists, and slab-ongrade, vertical fenestration and skylights. Each building component should be defined according to the performance requirements defined in ASHRAE , appendix G. Area of exterior walls, roofs and joists may differ between the Baseline Building design and Proposed Building deign to allow optimization of building design and material choice in building components. Customize the Baseline Building for the project to create the proposed building When the Baseline Building is created the design and material choices should be varied in order to accomplish positive environmental effects on the chosen impact categories. The final design results in a Proposed Building that meets needs of the 15

25 project and at the same time presents improvements from the Baseline Building design. The following parameters are necessary to keep the same to enable an accurate comparison: LCA scope requirements. The functional unit and the system boundary should be the same Size. The gross floor area must be the same. The two designs can have different massing, however the gross area has to be the same Function. The two buildings need to have the same function Orientation. The two buildings must have the same orientation Location. Both buildings have to be located in the same climate zone defined in ASHRAE , the buildings also have to be assumed to be on the same site Operating energy performance. Both models must meet the prerequisite Minimum Energy Performance by adhering to the requirements in ASHRAE Increasing wall mass or insulation in the Baseline Building to show dematerialization in the Proposed Building is not allowed Input the Baseline Building in the chosen tool When the Baseline Building is defined, the input data of the model design should be inserted in an appropriate LCA tool. The tool is used to benchmark the environmental impacts of various design alternatives. The results should be saved to enable comparison with the Proposed Building design and submitted to USGBC. Each design modification should be saved as a new LCA version so the project team can compare the embodied impacts of design alternatives. USGBC does not expect updated documentation for iterations of the LCA model during construction. Step 4 Select relevant impact measurement systems In this stage the appropriate output units for each LCA impact indicator should be selected based on the impact categories chosen to pursue. Step 5 Use LCA to make design decision that reduce environmental impacts In this step the proposed LCA model should be used to perform what if scenarios that analyses and support design decisions, but also to evaluate and select superior environmental assemblies and materials. 16

26 LEED v4 provides the following examples: Comparing the environmental consequences of building footprint and shape Evaluating different structural system types, such as load-bearing walls versus columns Defining the selection of building products and assemblies Optimizing structural system design (e.g. column spacing, slab depth) Step 6 Incorporate final LCA result The final step shall include a review of the results and incorporate the decisions of the design and material choices. Moreover a LCA narrative needs to be developed that describes the LCA assumptions, scope and baseline and proposed building. The LCA narrative shall include: LCA summary, showing outputs for each chosen impact category, global warming potential mandatory for all projects Table showing the relative percentages of all impact categories between the Baseline Building and Proposed Building design. Each design alternative that resulted in a change between the baseline and Proposed Building design needs to be described Data sets used to represent each material or assembly must be described, proxies may be deemed acceptable. Verification that the same data set is used for the parameters, which are necessary to keep the same The used database for characterization of the model and impact categories needs to be described Data source regarding the product replacements used in both building designs International tips The Baseline Building is based on minimum performance requirements regarding the structure and enclosure materials. These requirements are found in ASHRAE and should be followed for all projects. Projects outside the U.S. are expected to develop a Baseline Building representing typical construction materials for their region meeting regional building performance requirements. Additional documentation for meeting the regional requirements may be needed for reaching the credit (U.S. Green Building Council, 2013). 17

27 Required documentation Description of LCA assumptions, scope, and analysis process for Baseline Building and proposed building Life-cycle impact assessment summary showing outputs of Proposed Building with percentage change from Baseline Building for all impact indicators (U.S. Green Building Council, 2013) Minimum Energy Performance (EA) The intent of the prerequisite is to reduce the environmental and economic harms of excessive energy use by achieving a minimum level of energy efficiency for the building and its systems. Compliance with this prerequisite can be achieved by three alternative options, where Option 1 addresses whole-building energy simulation. As mentioned before the energy performance of the Baseline Building and Proposed Building design must meet the requirements of the prerequisite. The following section describes the prerequisite of LEED v4 (U.S. Green Building Council, 2013). Option 1: Whole-building energy simulation The energy performance for the Proposed Building has to demonstrate a minimum energy improvement of 5% (New Constructions BD+C), when comparing with the Baseline Building. The Baseline Building is created by changing the building envelope performance of the Proposed Building design to the requirements found in appendix G of ASHRAE (U.S. Green Building Council, 2014). The performance requirements of appendix G are used to determine the starting point of the building performance. The requirements include performance of the building envelope, HVAC, lightning, power etc. These requirements are usually applied to the proposed building energy model by changing the ingoing parameters to reflect the Baseline Building. Additional credits are available under the credit optimize energy performance in LEED v4. The credit allows project teams to achieve up to 18 additional points when improving the energy performance with 50% compared to the Baseline Building for new constructions (U.S. Green Building Council, 2013). Modeling of the Proposed Building must meet the following criteria: Compliance with mandatory provisions found in ASHRAE , Appendix G, with errata or a USGBC-approved equivalent standard for projects outside the U.S. Include all energy consumption and cost within the building project Include a comparison between a Baseline Building and the proposed building. The Baseline Building must comply with ASHRAE , Appendix G, with errata or a USGBC-approved equivalent standard for projects outside the U.S. 18

28 Documentation of the energy models (proposed- and Baseline Building) has to contain input assumptions of the unregulated loads. Unregulated loads (plug loads) includes equipment loads through electrical components such as office equipment and printers. These could cause unrealistic results if managed incorrectly. Both the baseline- and Proposed Building should document the unregulated loads used in the simulations. The following calculation method should be used: ASHRAE Alternatively, COMNET Modeling Guidelines and Procedures to record measures, which reduced the amount of, unregulated loads 2.4 Certification process The certification process in LEED follows a four-step approach, which is presented in Figure 4. The contents of each step are explained in this chapter gathered from USGBC website (U.S. Green Building Council, 2015). 1. Register 2. Apply 3. Review 4. Certify Figure 4, the certification process in LEED Step 1. Register Before registering the LEED project, certain requirements must be fulfilled. One of these is that all LEED projects need to meet the Minimum Project Requirements. The requirements contain criteria that each project needs to comply with before pursuing for LEED certification. All projects: Must be in a permanent location on existing land. This means all projects pursuing for LEED v4 certification must be constructed and operated on permanent and existing land. Projects that are intended to move at any point during their lifetime are not eligible for pursing LEED certification. Must use reasonable LEED boundaries. Reasonable boundaries means that all land associated with the project and is used for the buildings typical operations must be included. This includes primary land usage by the occupants, hardscape, septic or storm water treatment and landscaping. Must comply with project size requirements. All LEED projects need to comply with specific size requirements listed for each rating system. For example the rating system Building design and Construction (BD+C) contains a minimum gross floor area of 93 square meters (1.000 square feet) (U.S. Green Building Council, 2014). 19

29 When the minimum project requirements are attained an appropriate rating system is chosen for the project. Each project is then registered at LEED online. LEED online is a new web-based tool that is used for simplifying the documentation process through- out the certification process. LEED contains five different rating systems, presented in Table 3, which addresses the needs in different projects and building types. Each rating system has a set of achievable credits and prerequisites that guides the user to make appropriate design and operational decisions in an early stage to achieve the pursued credits and prerequisites. Table 3. The five different rating systems in LEED Rating Systems in LEED Abbreviation Building Design and Construction (BD+C) Interior Design and Construction (ID+C) Building Operations and Maintenance (O+M) Neighborhood Development (ND) Homes (HOMES) LEED projects must be registered under a single rating system for the total gross area, regardless if the project includes a mixed usage. In cases when several rating systems appear suitable for the project the 60/40 rule should be used, see Figure 5, to select an appropriative rating system. The rule specifies that the entire gross floor area should be assigned with appropriative rating system for each building part. The resulting percentages of the total gross area are then used to determine the appropriate rating system. < 40 % Should not use that rating system % Project specific situation > 60 % Should use that rating system Figure 5. The 60/40 rule for choosing rating system for LEED A rating system should not be used if less than 40 % of the total gross floor area is appropriate for that rating system. If a rating system is suitable for 60 % or more, then it should be used for the project. If the rating system falls between % of the total gross floor area, then the rating system needs to be assessed based on the project situation and decided accordingly (U.S. Green Building Council, 2014). When the minimum program requirements have been fulfilled and the rating system has been chosen the application should be submitted through LEED online. The 20

30 project is first registered when the project owner sings the certification agreement and submits payment for the project. Thereafter the project will be accessible in LEED online where the documentation process begins. Step 2. Apply At this step all prerequisites connected to the chosen rating system together with the credits each project wish to pursue shall be documented in LEED online. These shall be achieved by information collection, performed calculations and analysis. All analysis and documentation should be gathered at LEED online where after Green Building Certification Institute (GBCI) reviews which prerequisites and credits is achieved. The project has to reach all prerequisites connected to the selected rating system and at the same time collect enough credits to reach the certification level. All documentation needed to reach specific prerequisites and credits are later submitted for a preliminary review. During the preliminary review technical advice is given if additional correction is needed to achieve the pursued credits. Step 3. Review GBCI will review the application once the documentation has been submitted for the preliminary review. The documentation will be evaluated in compliance with credits and prerequisites through technical reviews. GBCI will notify the applicants within business days if additional information is needed to reach the prerequisites and credits chosen for the specific rating system. The results given in the preliminary review can be accepted as final or add new or revise the documentation or attempt to reach additional credits before the final review. A final review stage is optional and offered to projects that require supplementary or additional information in their application. GBCI allows alterations being made to the application, and suggest the additional documentation to be handed in within 25 business days after receiving the preliminary review. GBCI will notify within business days if additional revisions are needed or present the final certification score. The final LEED certification will be given including information regarding the approved and denied prerequisites and credits. Just like in the preliminary review the results can either be accepted as final, or revised and resubmitted through an appeal. Projects are allowed additional rounds of reviews by sending an appeal. This additional round of review is connected with a fee, which varies depending on the complexity involving the prerequisites and credits involved. The same approach applies as before preliminary and final review when assessing the submitted documentation regarding the prerequisites and credits. Additional appeals can be made if the project wishes to include more credits or renew the application. 21

31 Step 4. Certify Once the application is complete and the result from the final review is accepted, the project will be closed out meaning the certification level is final. The LEEDcertification consists of four different levels of certification. The number of points is related to the achieved credits, see Table 4. Platinum is the highest level of certification and certified is the lowest (U.S. Green Building Council, 2015). Table 4. Certification levels in LEED Certification Level Earned points LEED Certified LEED Silver LEED Gold LEED Platinum Findings from LEED The following chapter answers the two questions: What is needed to reach the credit Building Life-Cycle Impact Reduction for new constructions in LEED v4? Which requirements are mandatory to fulfill when designing a Baseline Building according to LEED v4? When assessing the MR credit, Building Life-Cycle Impact Reduction, option 4, specific requirements are mandatory to follow for compliance. Option 4, whole building life-cycle assessment should be used for new constructions (BD+C ) which could lead to earning 3-points. A Baseline Building should be modeled to define the starting point for the LCA. The Baseline Building design should be determined in early design process, which allows comparison between different design alternatives for the Proposed Building design. The LCA shall be conducted for the buildings structural elements and building enclosure. Optional material components may be included in the LCA, although no additional points are earned. These include interior non-structural walls and finishes. According to LEED v4, structural elements and building envelope include the following building components: Footing and foundations Structural pillars, columns etc. Structural wall assembly (from cladding to interior finishes) Structural floors and ceilings (not including finishes) Roof assemblies Parking structures, exclude parking lots Stair constructions 22

32 LEED v4 does not describe which materials or products are appropriate to select when creating the required building components for a Baseline Building. Each project is instead required to design the Baseline Building according to typical materials used in local building constructions. This provides projects with the flexibility of choosing the materials or products used in the required building components. However the Baseline Buildings envelope still needs to fulfill the performance and material requirements stated in ASHRAE regarding the building envelope. When comparing the Proposed Building design to the Baseline Building design, some parameters are required to be equal. These include: Same LCA system boundaries (cradle-to-grave) Same size (total gross floor area) Same intended function (e.g. office, residential, school etc.) Same orientation Location Operating energy performance, EA prerequisite Minimum Energy Performance Both design alternatives, baseline building and proposed building, must have the same energy performance and at the same time comply with the prerequisite of Minimum Energy Performance. This is achieved by demonstrating a building performance improvement of 5 % for new constructions. The energy improvement is compared to the same building design with the exception of performance values. For the energy Baseline Building the performance requirements of ASHRAE , appendix G are applied. The Proposed Building energy performance is then compared to the one with applied performance values from appendix G. LEED does not specify clearly when the Proposed Building design regarding the energy and LCA model should be created. One solution is to design the Baseline Building for LCA purposes first, where the material selection is chosen with regards to the performance requirements of appendix G. The Proposed Building is created through sensitivity analysis of material variation in the structural elements and building envelope. The two models, baseline building and proposed building design are ensured to follow the same energy performance. When the proposed energy model is finished all new parameters regarding the structural elements and building envelope is updated accordingly in the two LCA models. These include building envelope performance, HVAC, power, and lightning requirements. By doing this the Proposed Building regarding energy performance can be duplicated for the LCA study. Following this interactive procedure for developing both the energy models and LCA models ensure the energy performance is equal. The Baseline Building is modeled to represent typical material selection of the building envelope and 23

33 structural elements. The performance of the building envelope needs to follow the performance of the Proposed Building energy model. To achieve the MR credit, Building Life-Cycle Impact Reduction, a minimum of 10 % reduction needs to be demonstrated by the Proposed Building compared to the Baseline Building. The reduction shall be demonstrated for three out of six impact categories, where Global warming potential is mandatory for all projects. None of the six impact categories are allowed to increase with more than 5 %, compared to the Baseline Building. Another point is available through the Innovation (IN) credit by achieving 10 % reduction on all six impact categories. There are six impact categories to choose from when conducting a LCA, these include: Global warming potential (greenhouse gases), CO2-eqv. Depletion of the stratospheric ozone layer, in kg CFC-11 Acidification of land and water sources, in moles H+ or kg SO2 Eutrophication, in kg nitrogen or kg phosphate Formation of tropospheric ozone, in kg NOx or kg ethane Depletion of nonrenewable energy resources, in MJ For the LCA study the system boundary needs to be the same in both building, cradle-to-grave for at least 60 years of service life. The LCA should include lifecycle stages regarding the structural elements and building envelope materials, in accordance with ISO The LCA-stages A1 - A4, B1 - B7 and C1 - C4 should be assessed for each chosen impact category. The chosen datasets and tool must be compliant with ISO The performance requirements and product requirements for the chosen materials are found in ASHRAE

34 3 Building standards In the following chapter general information and requirement stated in the building standards ASHRAE and BBR 22 are presented. The intention is to present the requirements referred to in ASHRAE by LEED v4 for designing a Baseline Building. In the end of this part results from ASHRAE and BBR 22 are presented together with a comparison of the two standards. 3.1 ASHRAE General background Standard 90 was the precursor to the ASHRAE-standard. Standard 90 was published in 1975 and has since then been renewed several times and republished in 1980, 1989, and The revisions were made according to ANSI and ASHRAE maintenance procedures. As the technical innovation and economical aspects started to change faster, the ASHRAE Board of Directors voted in 1999 to place the standard under a continuing maintenance. This resulted in several updates each year through submission of addenda and/or errata (ANSI/ASHRAE/IES Standard , 2010). The new approach has been executed since the 2001 edition, since then the standard has been published each fall of every third year. The new arrangement allowed revisions to be submitted in form of addenda and errata within the deadline for the upcoming edition. Approved addenda and errata are applied to the current version and included in the new edition every third year. Committees welcome users to leave suggestions of improvements to the standard, where they are invited to use a continuous maintenance procedure regarding the forthcoming version. A standardized form Continuous Maintenance Proposals (CMP) is included in the back of each version, where users are allowed to submit addenda and errata. When the committees approve addenda and/or errata, notices are published on ASHRAE and IES web sites. The 2010 edition includes 109 addenda, which were approved by ASHRAE and IES Boards of Directors in previous 2007 edition. Also all known text errors found in the previous 2007 edition were corrected in the latest 2010 edition. The 90.1 standard is a dynamic document, which evolves together with the technical advances within the construction industry. There are significant changes made in the 2010 edition from the previous edition (ANSI/ASHRAE/IES Standard , 2010). Changes in the 2010 edition: Expanded Scope, which allows the 90.1 Standard to cover receptacles and process loads (e.g. data centers) More stringent requirements on the building envelope Lowered lighting power density, additional occupant sensing controls, mandatory daylighting requirements and a new five-zone exterior lightning power density table have been added 25

35 Higher equipment efficiencies, energy recovery demanded in more applications, economizers required in 4 more climates and more requirements on energy-conserving controls Modeling requirements, for LEED certification, have been refined and expanded (ANSI/ASHRAE/IES Standard , 2010) Appendix G LEED v4 refers to the Performance Rating Method in Appendix G when defining the Baseline Building and the proposed design. The rating may be based on either annual energy operating cost or energy consumption, depending on the evaluation method of the rating authority. The method for designing the Baseline Building and the Proposed Building designs is often used by energy-efficient and green building programs such as LEED. Option 4 of the MR credit, Building Life-Cycle Impact Reduction in LEED v4, states that the results shall be presented for each impact category in unit per gross floor area (e.g. CO2-eqv/m 2 ). The Performance Rating Method in appendix G provides a methodology for designers when comparing the Baseline Building performance with the Proposed Building performance. The method is intended for rating purposes only, it does not provide compliance with the Standard 90.1 standard. However, when simulating the Baseline Building all mandatory and prescriptive requirements in Standard 90.1 should be applied (ANSI/ASHRAE/IES Standard , 2011). The Baseline Building and Proposed Building shall comply with the mandatory provisions and requirements found in sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4 presented in Table 5. The mandatory building envelope provisions and requirements found in section 5.4 are necessary to comply with when pursuing the MR credit, Building Life-Cycle Impact Reduction in LEED v4. LEED v4 requires that building envelope and structural components are included when pursuing the MR credit for life-cycle assessment (ANSI/ASHRAE/IES Standard , 2011). Table 5. Displaying chapter and description which include mandatory provisions. Mandatory provisions Chapter description 5.4 Building envelope 6.4 Heating, ventilation and air conditioning 7.4 Service water heating 8.4 Power 9.4 Lightning 10.4 Other equipment The basic rule for modeling the Proposed Building envelope is to use final architectural drawings to determine the dimensions, building shape, surface orientations, opaque construction assemblies etc. The Baseline Building should have the same physical design as the proposed building. 26

36 Building components that should be kept the same: Conditioned floor area Roof, wall, glazing and other surface areas Surface tilts and orientations. The Performance Rating Method, appendix G, is useful when comparing the energy performance of a building to the minimum requirements of the standard. Several green building programs exist that gives points when operating a certain percentage better than the standard One of these includes the USGBC s LEED rating system, which states a prerequisite for complying with the minimum requirement of Standard 90.1, and offers points when reaching over the minimum requirements. All simulations performed to the Baseline Building and Proposed Building shall be documented and submitted to the rating authority for example, USGBC. The documentation shall include a description of the project, simulation program used (including version type), results from the performance value for both models, percentage improvement etc. (ANSI/ASHRAE/IES Standard , The calculation for determining the improved performance of the Proposed Building design is calculated in percentage improvement as following: 100 (Baseline building performance Proposed building perforance) Baseline building performance All computer simulations of both the Baseline Building design and Proposed Building design shall use the same: Simulation program Climate data Purchased energy rates (if cost is used as the metric) Schedules of operation (except for adjustments needed to account for energy efficiency features). DOE-2 and EnergyPlus are two simulation programs that are suitable to use when simulating the energy performance of both building designs. Specific requirements of accepted simulation programs are mentioned in Appendix G (ANSI/ASHRAE/IES Standard , 2011). Both the Baseline Building and Proposed Building needs to be located in the same climate zone. Tables D1 - D3 lists climate zones for United States and Canadian territory with additional to international climate zones. Projects outside the United States not listed in the international climate zone shall be determined by using the major climate type definitions. International projects outside the United States not covered in table D3 in appendix D of ASHRAE Should instead 27

37 determine their climate zone through thermal criteria described in Table 6. The thermal criteria is set on either heating degree-days (HDD) for 18 C or cooling degree-days (CDD) for 10 C. The mean value of HDD18 C and CDD10 C shall be determined for the specific location (ANSI/ASHRAE/IES Standard , 2010). Table 6. Major climate type definitions Zone number Climate type Thermal Criteria 1 Very Hot-Humid (1A), Dry (1B) 5000 < CDD10 C 2 Hot-Humid (2A), Dry (2B) 3500 < CDD10 C A, 3B Warm-Humid (3A), Dry (3B) 2500 < CDD10 C C Warm-Marine CDD10 C 2500 and HDD18 C A, 4B Mixed-Humid (4A), Dry (4B) CDD10 C 2500 and 2000 < HDD18 C C Mixed-Marine 2000 < HDD18 C A, 5B, Cool-Humid (5A), Dry (5B), Marine 3000 < HDD18 C C (5C) 6A, 6B Cold-Humid (6A), Dry (6B) 4000 < HDD18 C Very Cold 5000 < HDD18 C Subarctic 7000 < HDD18 C Mandatory provisions regarding the building envelope are stated in section 5.4. These describe the provisions and requirements on insulation installment, maximum air leakage, and rating of doors and windows. The building envelope contains specific performance requirements for conditioned spaces, and should either comply with non-residential, residential or semi heated requirements. These requirements are specific to the chosen climate zone. Section 5.4 refers to additional requirements found under section 5.5 or 5.6 and 5.8. Section 5.5 and 5.6 regards the chosen compliance path, where section 5.8 regards product information and installation requirements of insulation and fenestration and doors, see Figure 6 (ANSI/ASHRAE/IES Standard , 2010). 28

38 5. Building Envelope 5.1. General 5.2. Definition of Compliance Paths 5.4. Mandatory Provisions 5.5. Prescriptive Path 5.6. Building Envelope Trade- Off Option Section 11. Energy Cost Budget Method 5.7. Submittals 5.8.Products Figure 6. Layout of chapter 5 Building envelope. Prescriptive building envelope option The Prescriptive Path contains building envelope requirements for conditioned spaces which are divided for each climate zone 1-8. The investigated location Malmö is located in climate zone 5, which limited the investigation to this climate zone. The requirements are specified for eight different building components of the building envelope. The first six are presented in Table 7. Each criteria set includes all prescriptive requirements on roofs, floors, walls etc. These contain requirements off insulation level, minimum R-value and maximum U-value for a set of building products. The requirements are divided in three conditioning categories, nonresidential, residential and semi heated spaces. These requirements are found under section 5.5 Prescriptive Path and are mandatory to comply with when following the Compliance Method (ANSI/ASHRAE/IES Standard , 2010). 29

39 Table 7. Summary of building envelope performance requirements for residential conditioned space. Climate zone 5 Opaque elements Assembly U-value in W/(m 2 K) according to ASHRAE Insulation entirely above deck Roofs Metal Building Attic and other Mass Walls. above-grade Metal Building Steel-framed Wood-framed and other Walls. below-grade Below-grade wall Mass Floors Steel-joist Wood-framed and other Slab-on-grade floors Unheated Heated Opaque doors Swinging Non swinging Requirements of fenestrations are divided into vertical glazing and skylights, which are presented in Table 8. Fenestrations are grouped depending on the frame-type. Where the maximum U-value and Solar-heat gain coefficient (SHGC) is presented for each frame type. The fenestration area is limited to a window-to-wall ratio between 0-40 % of the total exterior wall area. Criteria for skylights are limited to 5 % of the total roof area, which also include specific U-value and SHGC for each skylight type. The window-to-wall limitations are specific for the prescriptive method, which only allow building with the same WWR to follow the Prescriptive Path (ANSI/ASHRAE/IES Standard , 2010). When using the Prescriptive Path each envelope component needs to comply with the prescriptive requirements of the standard and the mandatory provisions. Although there are possibilities to do some area-weighting averaging where one construction fails to meet the requirements as long as other constructions perform better (ANSI/ASHRAE/IES Standard , 2010). 30

40 Table 8. ASHRAE Criteria for fenestration, prescriptive path, climate zone 5 Climate zone 5 Fenestration in percentage Fenestration according to ASHRAE Vertical glazing Nonmetal framing (all) Metal framing (curtain wall/storefront) 0-40 % of wall Metal framing (entrance door) Metal framing (all other) Skylight with Curb. Glass % % Skylight with Curb. Plastic % % Skylight without Curb. All % % % of roof Building Envelope Trade-Off Option This method involves more work than the Prescriptive Path method, which offers designers more flexibility, where Building Envelope Trade-Off Option is permitted. Surfaces areas for each exterior wall and semi exterior wall must be calculated where wall areas must be calculated for each orientation. A short description between the difference of a Prescriptive Path and Building Envelope Trade-Off Option is shown in Table 9 (ANSI/ASHRAE/IES Standard , 2010). Table 9. Comparison of Prescriptive Path and Building Envelope Trade-Off Option Prescriptive Path Building Envelope Trade-Off Option Fenestration area Area take-offs U-factor compliance Window area is limited to a window-to-wall ratio of 40%, and skylights are limited to 5% of the roof area. It is only necessary to verify that the window-towall ratio and/or skylightroof ratio and material components follow the requirements. Not necessary when using the R-value option. Fenestration area is allowed to be greater than 40% as long as the envelope performance is improved over the requirements in the prescriptive option. Surface areas have to be calculated for each type and class of construction. Additionally the window and wall areas must be calculated for all major weather directions including, NE, SE, SW and NW. Required.

41 Product information and installation requirements Section 5.8, Product information and installation requirements contain specific requirements for products and states approved laboratory testing of each product. The products include insulation, fenestration and doors, baffles, lighting fixtures, ducts, plenums etc. The requirements are mandatory and are specific for each material (ANSI/ASHRAE/IES Standard , 2010). The requirements include, but are not limited to: Insulation materials shall have a clearly identified R-value identification mark provided by the manufacturer Insulation shall be installed in accordance with the manufacturers guidance and recommendations Loose-fill insulation shall not be used in attic/roof spaces where the slope of the ceiling is more than three in twelve All insulation shall be installed with full contact to the inside surface, all cavities should be filled with the insulation material Insulation on exterior surfaces should be covered with a protective material to prevent damage from sunlight, moisture, wind etc. Attics and mechanical rooms shall be provided with sufficient space to access the equipment without damaging the insulation Insulation materials with ground contact, slab-on-grade, shall have a water absorption rate of maximum 0,3% when tested with accordance to ASTM C272 U-factor, SHGC, air leakage rate shall be provided by the manufacturer and listed on a nameplate for each product (ANSI/ASHRAE/IES Standard , 2010) 3.2 BBR General background Boverket is the approved authority in Sweden that specifies the laws and regulations regarding constructions and buildings. These laws are called Boverkets byggregler (BBR) and were first published on the 1 st of January The BBR regulations are restricted by the Swedish parliament and government (Boverket, 2014). BBR includes regulations that are mandatory, these regulations are based on the building laws found in Plan- och bygglagen (PBL) and Plan- och byggförordningen (PBF) (Boverket, 2015). Aside from the regulations, BBR also includes general advices that comply with the building laws, these are not mandatory but following these ensures compliance with the building laws. A general advice are not binding, instead they only give recommendations how the building laws could be fulfilled (Boverket, 2014). BBR is based on functional requirements where a certain function should be fulfilled. 32

42 3.2.2 Building envelope requirements, BBR 22 BBR 22 only includes guidelines for compliance with Swedish national building regulations. These are divided into 9 chapters which are presented in Table 10. Table 10. Chapters in BBR 22 Chapter Content 1 Introduction 2 General rules 3 Accessibility, housing design, room height and operating areas 5 Fire protection 6 Hygiene, health and environment 7 Noise protection 8 Safety in use 9 Household energy Building envelope requirements BBR 22 includes specific building envelope requirements, these are presented as a mean U-value (W/(m 2 K)) for the whole building envelope. The building envelope includes exterior walls, exterior roof, slab on-grade, thermal bridges, windows and entrance doors. The mean U-value requirements is set to 0,40 W/(m 2 K). The mean U-value is weighted through the equation, see (1). Where definition of the heat transfer coefficient and thermal bridges complies with the two standards, SS- EN ISO 13789:2007 and SS 2430 (Boverket, 2015). n m p U m = ( i=1 U ia i + k=1 l k Ψ k + j=1 χ j ) W/(m 2 K) (1) A om Where: U i A i Ψ k l k X j A om The heat transfer coefficient stated in W/(m 2 K), for each building component The area of the building component is calculated from the inside of a heated space (m 2 ). For windows and doors the area should include the frame dimensions Is the heat transfer coefficient stated in W/(m K), for linear thermal bridge The length of indoor air in contact with the thermal bridge (m) Is the heat transfer coefficient stated in W/K of a point shaped thermal bridge The total area enclosed by the building envelope which separates the heated inside spaces from the outside (m 2 ). The building envelope includes all building components that separate the outside from 33

43 inside, including separating heated spaces from semi-heated (Boverket, 2015) Daylight requirements BBR 22 requires that all rooms occupied more than temporarily should provide sufficient access to direct daylight. This should be accommodated by the choice of orientation and design. The amount of daylight is not specified instead a general advice of minimum 10% window-to-floor area should be fulfilled (Boverket, 2015). 3.3 Findings from Building standards The following chapter answers the two questions: Which requirements are mandatory to follow when designing a Baseline Building according to LEED v4? Are there any similarities between ASHRAE and BBR 22? ASHRAE states specific performance requirements for materials used in the building envelope. These include exterior walls above and below grade, roofs, joists, slab-on-grade, opaque doors and fenestrations. LEED v4 refers to appendix G in ASHRAE when designing a Baseline Building for LCA purposes. Appendix G contains the performance rating method, which is used as a baseline for energy-efficient and green building programs. The Performance Rating Method provides a methodology for designers and energy analyst for calculating energyefficient improvements. The improvements are based on a Baseline Building complying with the requirements of the standard. However LEED v4 refers to this method when modelling a Baseline Building both for the energy performance and LCA purposes. This result in the same requirements specified for both analyses. Nevertheless the LCA Baseline Building design and Proposed Building design only account for the structural elements and building envelope materials. The Performance Rating Method refers to the mandatory provisions in the building envelope, HVAC, service water heating, power, lighting and other equipment. In the LCA baseline design only the mandatory provisions of the building envelope is required. Furthermore these refer to compliance path requirements, where either the Prescriptive Path 5.5 or Building Envelope Trade-Off Option 5.6 should be used. Choosing an appropriate compliance path is mandatory for complying with the requirements. The choice of compliance path is depending on the building design, where simple building shapes with a window-to-wall ratio between 0-40 % allow project teams to select a prescriptive path. The Prescriptive Path is a straightforward approach where a set of performance requirements are stated for each building component, for each climate zone. When complex shapes and designs are used in the Baseline Building the Building Envelope Trade-Off Option should be selected. In addition performance requirements of the building envelope components and product information and installation requirements 5.8 should be fulfilled. Building envelope requirement in section 5.5 include minimum R-values on insulation 34

44 materials and maximum U-value for the assembly of building components. These include exterior walls, roofs, slab-on-grade, floors, windows and opaque doors. Section 5.8 specifies a set of mandatory provisions regarding installation of insulating materials, maximum air leakage and rating of doors and windows in the building envelope. BBR on the other hand states functional requirements on building components of the building envelope. The functional requirement is intended to capture a specific function for the building envelope performance. The compliance path for reaching the function is unrestricted and allows various design options. As opposite to ASHRAE that uses a more detailed approach in the creation of the building envelope. The main difference between the requirements found in BBR and ASHRAE are that BBR states functional requirements, while ASHRAE states specific performance requirements. Following detailed performance requirements stated in ASHRAE will result in a Baseline Building which could be used to analyze the energy performance. In a similar way the Baseline Building design can be created for LCA purposes. In other words the mandatory requirements for the building envelope stated in ASHRAE represent a Baseline Building. In difference to the requirements in BBR which are based on U mean -values for the total building envelope, this enables projects to select and account for different type of materials. 35

45 Table 11. Differences in climate envelope requirements between ASHRAE and BBR 22 Climate zone 5 ASHRAE BBR Opaque elements Assembly U-factor in W/(m 2 K) according to ASHRAE Insulation entirely above deck U m -factor in W/(m 2 K) according to BBR Roofs Walls. above-grade Metal Building Attic and other Mass Metal Building Steel-framed Wood-framed and other Walls. below-grade Below-grade wall Mass Floors Steel-joist Wood-framed and other Slab-on-grade floors Opaque doors Fenestration Vertical glazing Skylight with Curb. Glass Skylight with Curb. Plastic Skylight without Curb. All Unheated Heated Swinging Non swinging Assembly max. U Nonmetal framing (all) 1.99 Metal framing (curtain 2.56 wall/storefront) Metal framing (entrance door) 4.54 Metal framing (all other) % % % % % %

46 Table 11 presents the differences in building envelope requirements found in ASHRAE and BBR 22. Complying with both BBR 22 and ASHRAE requirements regarding the building envelope is possible. Compliance is met by fulfilling the performance requirements of maximum U-value of the assemblies and at the same time ensures the U mean -value for all exterior surfaces to comply with the BBR functional requirements of the building envelope. In addition to the performance requirements for the building envelope, both standards include a fenestration limit. ASHRAE stats the limit in window-to-wall ratio and window-to-roof ratio, while BBR 22 stats it in window-to-floor area. The limits are presented in Table 12. Table 12. Differences in fenestration requirements between ASHRAE and BBR 22 Climate zone 5 Fenestration Vertical glazing Skylight with Curb. Glass Skylight with Curb. Plastic Skylight without Curb. All Fenestration percentage according to ASHRAE Nonmetal framing (all) Metal framing (curtain wall/storefront) Metal framing (entrance door) Metal framing (all other) % % % % % % 0-40 % of wall 0-5 % of roof Fenestration percentage according to BBR % of floor area 37

47 38

48 4 LCA In the third part the background of LCA is explained. Thereafter standards used when performing LCA and methods of how to perform LCA are presented. Results are presented in the end of this chapter. 4.1 General background During the 1960s the environmental awareness increased around the world. One of the reasons for this sudden awareness was the newly released book Silent spring written by the American biologist Rachel Carson. The book describes how the chemicals used by the modern human effect its surroundings. These conclusions were known by scientist, but had not reached the wide public or politicians. When the book spread, the side effects of using chemicals led to debates, which resulted in restrictions of chemical usage. Other events such as the energy crisis in 1973 and the Chernobyl disaster in 1986 led to increased awareness about how sensitive our society is to environmental problems. These events and acknowledge forced countries around the world to find solutions for solving this new threat to the environment (Rydh et al., 2002). The environmental problem has over time gone from being local to global, but also the strategies of solving the problems have changed. In the beginning of the industrialization it was believed that if the pollutants were spread, the nature would take care of it eventually. Although it was ruled out as a solution when the emissions increased and the impact of them were acknowledged. This was the beginning of a new mindset in the industry, it was understood that the whole process of the product had to be analyzed (Rydh et al., 2002). Most of the initiatives have been made on a global perspective. One of this initiatives were the United Nation s Brundtland report, were the saying sustainable development was spread and its defined as follows: Development that meet the needs of today without compromising the ability of future generations to meet their own needs Another initiative was made in 1992, it was The United Nation Conference in Environment and Development that was held in Rio de Janeiro. The World Business Council for Sustainable Development (WBCSD) that led the conference had earlier, around 1990, noticed that among companies there were an absence of uniformed rules and terminology, when assessing environmental problems. Therefor the WBCSD started a committee within the International Organization for Standardization (ISO) that would assess this problem. In 1993 the TC 207 committee was established, they were responsible for the environmental management forms, and since then the TC 207 has developed several standards within the so-called ISO series. One of these is the environmental management for LCA. Since the Rio de Janeiro conference other conferences and 39

49 initiatives about how to reduce the human s effect on the environment has been held (Carlson et al., 2011). 4.2 The ISO series In the 1990s the usage of LCA increased, the on-going interest led to environmental adjustments in production strategies. This growing interest created an increased demand for LCA analysis that was practical to use in the daily work. During the 1990s ISO started their work with creating a standard for the life-cycle methodology, which was published in 1997 and named ISO :1997. The ISO standard contributed to an increased usage of LCA, but it also gave the user tools for how the results should be communicated. Since then the LCA development has progressed and today it is usable in many different industries thanks to the usage of Environmental Product Declaration (EPD) (Carlson et al., 2011). According to ISO , LCA is a compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its life-cycle (Swedish Standards Institute, 2006). The LCA is based on two different standards. The ISO that describes the main principles and structure of how a LCA should be carried out. The other standard, the ISO defines details and recommendations of how the procedure of assessing an LCA should be carried out. Furthermore there are also specific documentation format to support the documentation process when assessing an LCA, the ISO/TS Additional to this there is also two other technical reports for how some parts of the assessment, ISO/TR is used for goal and scope definition and inventory analysis. The ISO/TR is used for to impact assessment situations. There exists many more standards in the ISO series, and there is an on-going development of new standards and updates of the ISO family (Carlson et al., 2011). The following list presents the latest updated version of the ISO families (ISO, u.d.): ISO 14040:2006 Environmental management Life-cycle assessment - Principles and framework ISO 14044:2006 Environmental management Life-cycle assessment Requirements and guidelines ISO/TS 14048:2002 Environmental management Life-cycle assessment Data documentation format ISO/TR 14049:2012 Environmental management Life-cycle assessment - Illustrative examples on how to apply ISO to goal and scope definition and inventory analysis 40

50 ISO/TR 14047:2012 Environmental management Life-cycle assessment - Illustrative examples on how to apply ISO to impact assessment situations How to perform an LCA according to ISO 14040/14044 The main principal structure of an LCA is described in ISO An LCA is carried out in order to reduce environmental impact by choosing the most ideal product. This is done by comparing different products, to be able to decide which product that has the lowest impact on the environment. A product could be defined as a system, object or service developed to meet the demand (Rydh et al., 2002). The LCA can be divided into four life-cycle stages, which are presented in following text (Bayer et al, 2010): Product Extraction of the raw material from the nature Transporting of the material to the manufacture Manufacturing of the material Building fabrication and packing and distribution of building projects Construction Process All activities relating to the actual building project construction Use (Building operation): Energy consumption Water usage Environmental waste generation Repair and replacement of building assemblies and systems Transport and equipment use for repair and replacement End-of-life Energy consumed and waste produced due to building demolition and disposal of materials to landfills, and transport of waste materials Recycling and reuse activities related to demolition waste also can be included and have negative impact ISO The life-cycle stages can be divided into subcategories, so-called module groups, which are used for analyzing an LCA and creating EPDs. The ISO describe how to perform an EPD for the construction industry, according to SS EN (Swedish Standards Institute, 2013): 41

51 An EPD communicates verifiable, accurate, non-misleading environmental information for products and their applications, thereby supporting scientifically based, fair choices and stimulating the potential for market driven continuous environmental improvement. To describe the life-cycle process the term cradle-to-grave is often used, from when the energy and material is extracted from the nature, cradle, to when it has been reversed to the nature, grave, once again (Carlson et al., 2011). The cradle-to-grave assessment includes the following life-cycle stages: Product, A1-A3 Construction process, A4-A5 Use, B1-B5 End-of-life, C1-C4 (Benefits D) In this analysis, cradle-to-grave, a fifth module, module D could be included, which contain benefits from the end-of-life. When an EPD is created, only module groups A1-A3 are mandatory, declarations of the other modules are optional. This system boundary creates a cradle-to-gate assessment. Further on the cradle-to-gate option, covers A1-A3 with additional, optional modules, for example A4, see Figure 7 (Swedish Standards Institute, 2013). PRODUCT CONSTRUCTION PROCESS USE END OF LIFE A1 A2 A3 A4 A5 B1 B2 B3 B4 B5 C1 C2 C3 C4 Extraction and upstream production Transport to factory Manufacturing Transport to site Construction / Installation Use Maintenance* Repair* Replacement* Refurbishment* De-construction Transport Waste processing Disposal B6 Operational energy use B7 Operational water use *(incl. production and transport of necessary material) Figure 7. Information module groups in a LCA 42

52 The purpose of the LCA is to contribute to product development and improvement, strategic planning, public policy making, marketing and other. These purposes are obtained by following the four phases of LCA, which are stated in ISO (Swedish Standards Institute, 2006). An LCA is conducted in four different phases, which are presented in Figure 8, with a description in the following text. Goal Definition and Scope Interpretation Inventory Analysis Impact Assessment Figure 8. LCA Phases Step 1. Goal Definition and Scope In this phase the product that will be analyzed should be presented, also the reason for the analysis, why it is done and what the result should be used for. This section should contain: The scope of the analysis What type of analysis that is carried out What impact categories that will be evaluated It might also be necessary to go back to this phase later in the process to optimize and clarify the goal definition and scope. Step 2. Inventory Analysis In this phase all data from resources, raw material, waste, emission from the production should be gathered and put in the process flow chart in relation to suitable functional unit. The collected data should present input and output in order to perform a detailed inventory analysis. In this part a software and/or database could be essential, so that a material not have to be analyzed individual every time a LCA is performed. The simplest tools are spreadsheets, but there are also more complicated software s. Step 3. Impact Assessment During the impact assessment the emissions from the analyzed product is converted into how the impact on humans and the eco-system. The data from the inventory 43

53 analysis is categorized in the right impact category. There is none impact framework, which means that the LCA user could choose which categories that should be analyzed. Step 4. Interpretation The impact of the product should be evaluated throughout the whole LCA, in order to lower the environmental impact. Therefor could an LCA be seen as an iterative process where it might be necessary to go back and forth between the phases in order to make environmental friendly decisions (Bayer et al, 2010). 4.3 Findings from LCA The following chapter answers the two questions: What should is included in ISO and ISO ? What is included in a cradle-to-grave LCA? Today, an LCA is based on two different standards. The ISO that describes the main principles and structure of how a LCA should be carried out. The other standard, the ISO defines details and recommendations of how the procedure of assessing an LCA should be carried out. Further on to there are additional standards within the ISO family. When performing a LCA in accordance with ISO 14040, there are four different lifecycle stages; product, construction process, use and end-of-life. Occasionally a fifth life-cycle stage is included which contains benefits from the end-of-life stage, which is voluntary. The life-cycle stages contain subcategories, so-called module groups. When performing an LCA there are different system boundaries that are used, depending on which module groups that are included. Two examples of system boundaries are: Cradle-to-grave: Product, A1-A3 Construction process, A4-A5 Use, B1-B5 End-of-life, C1-C4 (Benefits, D) Cradle-to-gate: Product, A1-A3 LEEDv4 requests that the LCA is performed according to a cradle-to-grave assessment. 44

54 5 Development of a Baseline Building The fourth part explains the method that was used in order to investigate whether it was possible to create a general Baseline Building representing the Swedish building stock. The Baseline Building should include structural element and building components according to the requirements found in LEED, ASHRAE and BBR. As a first step surveys regarding newly built multi-family dwellings in Sweden were analyzed. In addition to these surveys, information was gathered from the BETSI project, Wikells Sektionsfakta, material suppliers and internal data from a construction company. When all information was analyzed, the Baseline Building was created. 5.1 Analysis of the Swedish building stock Statistical data was gathered to find typical materials/building components used in Swedish buildings. Databases and projects containing building specific information of the Swedish building stock were gathered. The selected data was based on the credit Building Life-Cycle Impact Reduction in LEED v4, which state a Baseline Building should represent typical constructions for their region (U.S. Green Building Council, 2013). In addition to this the Baseline Building should fulfill the criteria and descriptions set in ASHRAE , according to LEED v4. The analysis of the Swedish building stock was carried out in a step-by-step approach. In the first step, surveys conducted by SCB were gathered and analyzed to investigate typical building materials used in the building envelope. Secondly information from the Swedish national project BETSI was investigated. Any missing information needed for developing a Baseline Building according LEED v4 was supplemented from material suppliers. As a fourth and final step drawings of standard building designs and constructions were gathered from Skanska internal database (VSAA). Each project/database used for the analysis is presented in Figure 9. The investigated projects and databases are described in the following text. SCB data BETSI Literature study Wikells Sektionsfakta Swedish Baseline Building Material suppliers Skanska VSAA Figure 9. Overview of the data collection process used in this report 45

55 SCB data Statistika CentralByrån (SCB) is roughly translated in English to the Swedish Central bureau of statistics. SCB is a public administrate authority in Sweden, which provides official and public statistics for decision-making, debate and research. The choice of gathered statistics is mainly decided by the Swedish government and various authorities, but also by researches and private businesses. The purpose of SCB is to develop, produce and distribute statistics, and support international organizations with statistical data (SCB, 2014). In 2009 SCB changed their policy regarding public information, because of this it was not possible to obtain information of primary data later than Therefor data from 2009 and earlier was used in order to process the data as desired for this project. The BETSI-project In 2006 Boverket got the mission from the Swedish government to investigate the condition of the Swedish building stock. The project named Byggnaders energianvändning, tekniska status och inomhusmiljö (BETSI) was carried out all over the country by conducting surveys and inspections. During the period of about 1800 inspections and measurements in 30 different municipalities was carried out. Boverket investigated the buildings energy consumptions, technical status and indoor environment. At the same time the inhabitants got to answer surveys about how they experienced the indoor environment and and questions about their health. The report was finalized first in 2009 where the result of the task was presented. One of the resulting project reports were Så mår våra hus Redovisning av regeringsuppdrag beträffande byggnaders tekniska utformning m.m., which was used in this investigation (Boverket, 2009). Skanska VSAA When all information regarding the building envelope components and material selection was identified, standard building designs were gathered. These were collected from Skanska s internal database Vårt Sätt Att Arbeta (VSAA) = Our way of working, which provided architectural drawings for standardized multi-family dwelling design. Wikells Sektionsfakta Wikells Sektionsfakta contains data regarding ingoing material for different building components. The program was in this case used as a measure to estimate material consumption for each building component. Wikells Sektionsfakta is based on a standard pricelist from different industries in the construction business. Besides material consumption and cost, the program gives the user in information regarding proposed building constructions, waste and time spent by the craftsmen (Wikells Sektionsfakta, 2015). 46

56 Material suppliers Questions regarding windows and doors were excluded in the surveys carried out by SCB and was therefore complemented from material suppliers. Two of the largest Swedish window suppliers, Elitfönster and SP fönster, were contacted in order to find the most common window type sold to newly constructed multi-family dwellings in Sweden. The following questions were asked: Does any statistics of the most common window type for newly produced multi-family dwellings exist? Which main components are included in that window? Does EPDs exist for that window type? Data collection All collected data regarding the structure elements and building envelope of the analyzed buildings were gathered from SCB, primary source, with additional data from the BETSI project, Wikells Sektionsfakta and material suppliers, secondary source. The gathered SCB data contained conducted surveys regarding newly constructed dwellings between , including information regarding material choice, technical solutions and miscellaneous information. The scope for the data collection was limited to only include the past 10 years of available data and limited to 3-8 stories multi-family dwellings. The number of surveys within the chosen scope was limited to Building material SCB contain statistical data which was used as a primary source, while the BETSI project and Wikells Sektionsfakta was used as a secondary source, as a complement to the statistical data. The secondary data was used to determine the amount of building materials based on common U-values derived from BETSI project. Additional data and information was gathered from material suppliers to fill out any missing information regarding materials in the primary source. SCB and the BETSI project were based on different time periods; where SCB gathers yearly statistical data, compared to BETSI, which divide the data in time spans of 10 years ( ). Due to the variations in time periods the comparison between the data in the BETSI project and the processed data from SCB only provides rough estimations of the building envelope performance. The gathered data was divided into four main components of the building envelope and structural bearing. In addition, two more questions were analyzed regarding common building shapes and manufacturing method. These were selected based on the requirements of LEED v4 when creating a Baseline Building for LCA purpose 47

57 (U.S. Green Building Council, 2013). The six questions investigated are presented in Error! Reference source not found.. Building shape Structural component Manufacturing method Façade material Roofing material Window/ door type Figure 10. The six questions investigated for determining a Baseline Building. Each question is connected to a number of variables, containing different material selections of each building component. Five out of six building components are presented in Table 13. The sixth building component windows and doors were excluded in the SCB-surveys. Because of this, additional information regarding window and doors parameters were necessary to complement, which were gathered from contact with material suppliers. The following ingoing parameters for windows were requested: Material included in component Number of panes Gas Low-e coating Frame type 48

58 Table 13. The five main questions and variables gathered from SCB surveys. Building Structural Manufacturing Façade Roofing shape element method material material Apartment Wood Completely Wood Concrete Block prefabricated tiles Building Block Concrete Partly Concrete Mud-brick prefabricated External Steel Built-on-site Brick Sheet metal entrance house Terraced house Other Lime brick Felt roof Other Plaster Other Sheet metal Other Variables Apartment Block Building Block External entrance house Terraced house Other = Lamellhus, BBR definition: Houses that have two or more stories above the round and at least two interior staircases. The building is not angled or incorporated with house on the neighboring property. = Punkthus, BBR definition: Detached building with several floors above ground with one, usually centrally located, stairwells. = Loftgångshus, BBR definition: Multi-family dwellings with access to the apartments via exterior corridors, an elongated balcony along the building facade. Balcony access may have surface mounted or built staircase. = Flerbostadsvilla, BBR definition: Small villa-like building with a few apartments, however always at least three residential apartments (Boverket, ). All other designs that cannot be defined by the four other alternatives Data process and analysis All surveys gathered from SCB were processed in the computer program, Microsoft Excel. The analysis of the data was carried out in a two separate studies, One-way tables and Cross-Tabulation (The Statistical Services Centre, 2001). 49

59 One-way tables use a more straightforward approach since each question was analyzed independently from each other. This analysis was made to find which variable was most common for each question answering the choice of material in building components. The frequencies and percentages of each question was presented in tables which were derived from formulas, where COUNTIF, VLOOKUP and Pivot tables were used in Microsoft excel. The survey questions were analyzed to determine which answer that was most common for newly constructed multi-family dwellings in Sweden, of 3-8 stories during Analyses were conducted for the five different survey questions, presented in Table 14 - Table 18. Each question was coded by SCB, described as SCB code in the tables. Questions regarding materials, where more than one answer could be correct, only the main material choice be selected. For question 11, regarding manufacturing methods, the three different manufacturing methods were missing clear definitions, for what was the difference between the three answers. Table 14. SCB survey question regarding building shapes Question 5: What building shape is chosen for the constructed multi-family dwelling? SCB Code Survey answer 21 Apartment Block 22 Building Block 23 External entrance house 24 Terrace house 25 Other Table 15. SCB survey question regarding material in structural component Question 10: What material is chosen for the building structure? SCB Code Survey answer 1 Wood 2 Concrete 3 Steel 9 Other Table 16. SCB survey question regarding manufacturing method of the structural component. Question 11: Which type of manufacturing method is used for the structural material? SCB Code Survey answer 1 Completely prefabricated 2 Partly prefabricated 3 Built-on-site 50

60 Table 17. SCB survey question regarding the facade material. Question 12: What is the chosen facade material? SCB Code Survey answer 1 Wood 2 Concrete 3 Brick 4 Lime brick 5 Plaster 6 Sheet metal 9 Other Table 18. SCB survey question regarding the roofing material. Question 13: What is the chosen roofing material? SCB Code Survey answer 1 Concrete tiles 2 Mud-brick 3 Sheet metal 4 Felt roof 9 Other Cross-tabulation Cross-tabulation method investigates questions in relation to each other to find the most common combination. The combinations were analyzed by using pivot tables to enable a visualization of the available combinations found in the surveys. The analysis was divided into two pivot tables for each building shape. This approach left four of the main components to be sorted in the pivot table. The first two questions, structural element and manufacturing method, were inserted into rows while the remaining two, façade material and roofing material, were used in the columns, as shown in Figure 11. COLUMNS Facade material Roofing material ROWS Structural element Manufacturing method VALUES / % Figure 11. Layout and input values of the studied pivot table. 51

61 The pivot table offered a large variety of combinations from the analyzed surveys; these were therefore restricted to only account for the combinations occurring more than 7 % in all of the surveys. 5.2 Starting point for baseline The following part describes the process of how the Baseline Building was created. As a first step a building design was chosen based on statistical review and conceptual designs from Skanska. The conceptual building design was used as a starting point for the Baseline Building design. Thereafter the material selection for each building component of the building envelope was transferred from SCB, BETSI, and Wikells Sektionsfakta together with information from material suppliers Starting point for building design To be able to create a Baseline Building a defined building design was needed. The building design was obtained from standardized multi-family dwellings created and used by Skanska. These standardized multi-family dwellings contained information regarding building dimensions and construction. Building dimensions were taken from the drawings. The building dimensions were used to developing the Baseline Building while the material selection for the building envelope and was based on the statistical review. No calculations for dimensioning the constructions were made; the chosen dimensions were only based on assumption from the standardized drawings from Skanska Starting point for building components The constructions for the building components in the Baseline Building were based on the result found in analysis of the Swedish building stock. The constructions were derived from Wikells Sektionsfakta, which was used in order to estimate the quantities of used material in building components. Additional information and definitions were gathered from the largest concrete prefabrication companies in Sweden, Strängbetong and Abetong, to make valid assumptions of construction types. The calculated U-value of the assumed building components were compared to the BETSI average U-values for multi-family dwellings in The ASHRAE and BBR requirements for maximum allowed U-value were compared with the calculated results. 5.3 Analysis of LCA In this part the LCA of the analyzed building components are presented. The LCA of the building components were analyzed in a simplified LCA tool, which normally is used by Skanska. This part presents how the analysis was carried out, which parameters that were analyzed and how they were varied. The used simplified LCA tool is a simplified version of the more advanced LCAprogram ECO 2. The simplified LCA tool is limited to only analyze the module 52

62 groups, A1-A3, while ECO 2 can investigate the whole cradle-to-grave system boundary. Both the simplified tool and ECO 2 uses the same emission factors and provides generic data for the different materials. This means that the results that are presented only present a mean value for each material. The emission factors are calculated by IVL, the Swedish Environmental Research Institute (IVL, 2013). Currently the simplified tool used data from The tool includes sections A1-A3 for the product stage in the LCA, which means that the processes for raw material, transportation to the factory and manufacturing is included. Since LEED also includes B1 - B7 and C1 - C4, the LCA s were not complete, see Figure 12. Limitations in the simplified LCA tool: Only includes LCA group modules A1-A3 Only produce results for GWP (CO 2 -eqv.) Has a limited material data base PRODUCT CONSTRUCTION PROCESS USE END OF LIFE A1 A2 A3 A4 A5 B1 B2 B3 B4 B5 C1 C2 C3 C4 Extraction and upstream production Transport to factory Manufacturing Transport to site Construction / Installation Use Maintenance* Repair* Replacement* Refurbishment* De-construction Transport Waste processing Disposal B7 Operational water use *(incl. production and transport of necessary material) Figure 12. Life-cycle stages included in LCA Operational energy use LCA of starting point The following building components were included when designing the Baseline Building. These building components were also used for the LCA of the starting point Baseline Building. The following building components were included in the Baseline Building: Slab-on-grade B6 53

63 Footing (only enclosing part of slab-on-grade) Slab Roof slab Roof construction (incl. coverings) Load bearing inner walls Exterior walls Exterior windows Exterior doors The following building components were excluded in the Baseline Building: Stair construction Interior finishes of walls Footing (load-bearing slab-on-grade constructions) Drainage material such as macadam In the following part the building constructions that were used as a starting point for the Baseline Building are described. These were investigated to decide which building components that contributed the most to the global warming potential. LCA for different building components Furthermore the LCA was carried out in two steps, as a first step 1 m 2 of each building component was analyzed individually, to evaluate which solutions that had the most reduction of CO 2 -eqv. A sensitivity analysis was carried out in order to estimate which building components that influenced the outcome of the LCA the most. The following alternatives were investigated in the sensitivity analysis: Different insulation materials Different suppliers of reinforcement steel Different concrete qualities Variation of roofing materials LCA for whole building As a second step of the LCA analysis a whole building analysis was carried out. The analysis was also carried out for the three different heights of the buildings, 3, 6 and 8 stories. In this whole building analysis, the solutions with the most reduction of CO 2 -eqv was applied. 54

64 6 Result 6.1 Analysis of the Swedish building stock The first part presents the results from the one-way-table study, where each survey question was analyzed. This is followed by the cross tabulation study that analyzes the same questions found in the surveys, but coupled with relations to find the most common combination. Thereafter a summary of common U-values found in the BETSI-project is presented. The combinations that are found to be most common in the survey answers will be used in the development of a Baseline Building. Building shape The results show that two building shapes apartment building and Building Block are the most common shapes built in Sweden during , see Figure 13. These two building shapes were analyzed further since they account for 89 % of 2441 conducted surveys. This reduced the number of surveys to 2172 when excluding External Entrance House, Terraced House and Other building shapes. 7% 2% 2% Building shapes found in SCB surveys 46% 43% Apartment block Building block External entrance house Terrace house Other Figure 13. The most common building shapes constructed during Structural component The results show that concrete was the most common material used in the building structure of both building shapes, see Figure 14. When comparing the two results, the Building Blocks have a lower percentage built out of concrete since wooden and steel structure was more common in this case. Both Apartment Blocks and Building Blocks constructed in concrete represent the largest percentage of the total conducted surveys. Due to this only concrete as structural components is analyzed for the manufacturing method. This limits the number of conducted surveys to

65 Structural component, Apartment Block Structural component, Building Block 4% 1% 2% 93% Wood Concrete Steel Other 5% 1% 6% 88% Wood Concrete Steel Other Figure 14. Most common material selection for the structural bearing. Manufacturing method The analysis present small variations in manufacturing method between the two building shapes, the frequency of built-on-site is similar for both Apartment Block and Building Block, see Figure 15. The two prefabrication methods, completely prefabricated and partly prefabricated, show slight differences in frequency in relation to the building shape. However for both building shapes, Apartment Block and Building Block partly prefabricated is the most common. Manufacturing method, Apartment Block Manufacturing method, Building Block 32% 16% Completely prefabricated 32% 21% Completely prefabricated Partly prefabricated Partly prefabricated 52% Built on site 47% Built on site Figure 15. Most common manufacturing method for the structural bearing. Façade material There are no significant material variations between the both building shapes, see Figure 16. Plaster is the predominate material used for façade finish for both 56

66 Apartment Blocks with 72 % and Building Blocks with 69 %, followed by brick and concrete. Facade material, Apartment Block Facade material, Building Block Wood Wood 1% 0% 6% 8% 13% 0% Concrete Brick Lime brick Plaster 2% 5% 11% 1% 12% 0% Concrete Brick Lime brick Plaster 72% Sheet metal Other 69% Sheet metal Other Figure 16. Most common façade material choice of the two building shapes. Roofing material Figure 17 presents the differences of material choice in the roofing material for both building shapes. The three most common materials used for both building shapes are metal sheet, roofing felt and concrete tiles, in that order. The biggest difference between roofing materials in Apartment Blocks and Building Blocks is the usage of concrete tiles and roofing felt. Apartment Block has a higher usage of concrete tiles compared to roofing felt and vice versa. Roofing material, Apartment Block Roofing material, Building Block 28% 3% 24% 2% Concrete tiles Mud-brick Sheet metal 33% 3% 17% 6% Concrete tiles Mud-brick Sheet metal 43% Felt roof Other 41% Felt roof Other Figure 17. Most common material choice for the roofing materials. 57

67 Cross tabulation Results from the cross tabulation study are presented in tables for each building shape, Apartment Block and Building Block. The results present the most common building materials combinations used in regards to the chosen scope of the thesis. Apartment Block The results regarding common combinations used in Apartment Blocks present four combinations that occur more than 7 % of the total number of surveys Each building shapes is presented alone, where Apartment Block account for 1060 surveys and Building Blocks 1112 for the total. The most common combination in Apartment Blocks are presented in Table 19. Results show that the most common combination consists of a partly prefabricated concrete structure with plaster façade and metal sheet roofing in 21.1 %. Study show that all four combinations have used concrete as the structural material and plaster as façade material. This matches the results from the one-way table studies, which indicated a high usage of these materials. The only material variation found in the four building combinations affects the manufacturing method, which is either partly prefabricated or built-on-site and variation in the roofing material sheet metal, roofing felt and concrete tiles. Table 19. The most common building combinations from the cross tabulation study regarding Apartment Blocks. Apartment Block Combination Structural Concrete Concrete Concrete Concrete component Manufacturing Partly Partly Partly Built-on-site method prefabricated prefabricated prefabricated Facade Plaster Plaster Plaster Plaster material Roofing Sheet metal Felt roof Concrete tiles Felt roof material Percentage 21.1% 8.8% 8.7% 7.2% Similar results were found when analyzing the Building Blocks. The results are presented in Table 20 and displays similar combinations for both building shapes. The most common combination turned out to consist of a partly prefabricated concrete structure with plaster façade and metal sheet roofing, 17.8 %. The spread between the four most common combinations is however smaller for Building Blocks compared to Apartment Blocks. 58

68 Both building shapes use concrete in the structural components and plaster in the façade materials. The combinations vary on the manufacturing method of structural concrete and chosen materials in the roof. Combination one, two and four are same for both building shapes, where the percentage varies for each building shape. However the third most common combination presents differences in the choice of manufacturing method and roofing material. The percentages for the third combination in both Apartment Block and Building Block vary slightly in the percentages 8.7 % compared to 8.9 % The third combination of Apartment Blocks use a partly prefabricated concrete structure and concrete tiles in the roofing material, while Building Blocks uses built-on-site concrete structure and sheet metal for the roofing material. Table 20. The most common building combinations from the cross tabulation study regarding Building Blocks Building Block Combination Structural Concrete Concrete Concrete Concrete component Manufacturing Partly Partly Built-on-site Built-on-site method prefabricated prefabricated Facade material Plaster Plaster Plaster Plaster Roofing Sheet metal Felt roof Sheet metal Felt roof material Percentage 17.8% 11.3% 8.9% 7.4% 6.2 Starting point for Baseline Building The structural and building envelope components were based on the collected data from SCB surveys analysis and material suppliers. Some assumptions were made for the materials of the statistical analysis; these were made due to the lack of definitions of the chosen construction types Starting point for building design In order to represent the investigated building shapes, Apartment Block and Building Block, two building designs were chosen, Frida and Linnea. The two buildings were within the thesis scope, multi-family dwellings of 3-8 stories. Each building shapes is presented in Figure 18 and Figure 19 with general information in Table 21 and Table 22. The used data for the fenestration is presented in 59

69 Appendix B. Fenestrations. Figure 18. Apartment Block Frida, 3, 6 and 8 stories Table 21. Building information of Apartment Block Frida Frida General information Building dimensions / m Building shape Building Block Length Rooms/apartment 1-4 rooms Width Apartment size / m Story height 2.83 Number of stories 3-8 Attic height 0.55 Roof length Roof width

70 Figure 19. Apartment Block Linnea, 3, 6 and 8 stories Table 22. Building information of Building Block Linnea Linnea General information Building dimensions / m Building shape Building Block Length Rooms/apartment rooms Width Apartment size / m Story height 2.83 Number of stories 3-8 Attic height 1.94 Roof length Roof width The two building dimensions and designs were used for representing the Baseline Building. The most common materials found during the statistical analysis were applied to the structural components and the building envelope. Where each building component slab on ground, roof and wall assemblies, were assumed to reflect common building practices found in Wikells Sektionsfakta database and from internal database from Skanska. These material combinations were combined with the standardized building models to develop the Baseline Building. Building dimensions were extracted from 2D models, drawn in AutoCad of the two building models, Frida and Linnea. The extracted area is compiled in Table 23 and Table 24, which were used further for calculating materials amounts for different construction methods. 61

71 The parameters gathered from Skanska conceptual buildings included: Total external wall area Total external roof area Total gross floor area Total slab area Total window area Number of stories Window-to-wall ratio Table 23. Model input data for Apartment Block Frida Model input data Frida Number of stories Building components Unit Total external wall m Total inner wall area (load bearing) m Total roof area m Total slab area m Total footing length m Total slab-on-grade area m Total roof-slab area m Total window area m Window-to-wall ratio %

72 Table 24. Model input data for Building Block Linnea Model input Linnea Number of stories Building components Unit Total external wall m Total inner wall area (load bearing) m Total roof area m Total slab area m Total footing length m Total slab-on-grade area m Total roof-slab area m Total window area m Window-to-wall ratio %

73 6.2.2 Starting point for building components In the following chapter the assumptions and simplifications regarding the choice of construction type for each building component is explained. The building components are based on results from SCB, Wikells Sektionsfakta and common construction principles. The drawings for the building components are presented in Appendix C. Architectural drawings. Slab-on-grade Slab-on-grade was assumed to 100mm of concrete with 300mm of underlying EPS insulation. The amount of reinforcement and construction assembly was collected from Wikells Sektionsfakta. No site development or material filling (macadam) was assumed for the given construction. The slab-on-grade assembly is presented in Table 25. Table 25. Starting point for slab-on-grade Material Quantity Amount Unit 100 Concrete C25/30 Area 1.00 m² Reinforcement Area 1.20 m² 100 Cellular plastic Area 1.00 m² 100 Cellular plastic Area 1.00 m² 100 Cellular plastic Area 1.00 m² Joist construction The joist constructions only include the structural bearing for each floor excluding any finishes made. HD/F joists where chosen for the floor construction in the Baseline Building, the thickness was assumed to 200mm, see Table 26. Table 26. Starting point for joist Material Quantity Amount Unit 200 HD/F Concrete C25/30 Area 1.00 m² Reinforcement Mass kg Roof covering Only one question in the analyzed surveys was concerning the roof type, What is the chosen roofing material? The statistical analysis only presented the most common roofing material. The results from the analysis show that sheet metal was most commonly used material. The construction type was unknown and assumptions were made on the roof construction, see Table

74 Table 27. Starting point for roof covering assembly Material Quantity Amount Unit Steel roofing Area 1.00 m² Paperboard Area 1.00 m² 22 Tongue and groove panel Area 1.00 m² 45x145 roof ridge-c14 c1200 Length 1.20 m 45x95 roof ridge-c14 c1600 Length 0.70 m Nail-plate 60x240x2.0 Pieces Brackets, nails Pieces Roof construction The roof construction was assumed to be a cold attic, with a concrete roof joist entirely insulated with loose wool insulation. The same concrete quality and construction type was selected as joists between each story, see Table 28. Table 28. Starting point for roof construction assembly. Material Quantity Amount Unit 450 loose wool fill Area 1.00 m² 200 HD/F Concrete C25/30 Area 1.00 m² Reinforcement Mass kg External wall The most common material combinations regarding the external wall were derived from the SCB survey analysis. This included three questions concerning the type of exterior wall: What material is chosen for the building structure? Which type of manufacturing method is used for the structural material? What material is chosen for the façade material? The results showed the most typical combinations for both building shapes were partly prefabricated concrete structures with a plaster finish. Since the manufacturing methods was not defined the in the surveys each variable had to be assumed. These were based on contact with concrete suppliers, Abetong and Strängbetong and construction engineers at Skanska regarding the construction industries definition of partly prefabricated concrete structures. Based on the information, two assumptions were made of the structural components. The first assumption, partly prefabricated 1, a so-called sandwich construction, included two layers of concrete C25/30 with a layer of EPS insulation in-between and a plaster façade. The wall is delivered finished where the façade material was assumed to be built-on-site. The second version, partly prefabricated 2, was assumed to be a singleelement concrete C25/30 construction where the external layer of mineral wool 65

75 insulation and plaster façade was built-on-site. The material amounts for the assemblies where gathered from Wikells Sektionsfakta database, Skanska VSAA and Strängbetong, see Figure 20, Table 29 and Table 30 for the chosen construction types. Figure 20. Two construction alternatives regarding the assembly of the exterior wall. Partly prefabricated 1, sandwich wall element and partly prefabricated 2, single-element concrete wall (Strängbetong, 2014). Table 29. Starting point for Sandwich concrete element assembly Material Quantity Amount Unit Plaster Area 1.00 m² 70 Concrete C25/30 Area 1.00 m² Reinforcement Mas 3.80 kg 200 EPS Area 1.00 m² 150 Concrete C25/30 Area 1.00 m² Reinforcement Mass 7.60 kg 66

76 Table 30. Starting point for Single-element concrete wall assembly. Material Quantity Amount Unit Plaster Area 1.00 m² 200 Mineral wool Area 1.00 m² 150 Concrete C25/30 Area 1.00 m² Reinforcement Mass 1.00 kg Reinforcement Mass 6.60 kg Windows and doors One of the largest window suppliers, Elitfönster, was contacted regarding common window types sold to newly constructed multi-family dwellings. Elitfönster had no statistical data to support which was the most sold window for each building type. Elitfönster still they knew within the company that the two products most used for this kind of project were: Elit xceed outwards and Elit xceed inwards. Both windows have a wooden frame and stash with an exterior aluminum covering. The outward window has a lower U-value, but the inward window reduces noise better and was therefore a more common choice for buildings in cities. The U-value of these windows varies up to 1.2 W/(m 2 K). The other producer, SP fönster states that they have two popular window types for multi-family dwellings. These were top-swing windows with a wooden frame and stash with an exterior aluminum covering. The second one was a 2+1 inward going window with wooden frame and aluminum covering. The U-value of these windows varies between W/(m 2 K). From both producers the technical data and EPDs for the different windows were received, which was analyzed in order to pinpoint the most common window for multi-family dwellings. Based on this information from the two window suppliers, the windows were assumed to consist of three glass panes, aluminum coated wooden frames without gas. The same product assembly was assumed for the exterior doors, since doors were glazed in the two building designs, Frida and Linnea. Summary of U-values from the BETSI-project To ensure the chosen construction of each building component is represented to the Swedish building stock, U-value calculation were made and compared to BETSI project results. In addition the requirements from ASHRAE and BBR regarding the performance of the building envelope was fulfilled. The results of the building envelope performance and building product assembly are presented in Table 31 Table 34. These results present the fulfillment of the BBR requirement regarding a maximum of 0.40 W/(m2 K) in mean U-value (Boverket, 2015). The complete U- value calculation is presented in Appendix A. U-value calculation. 67

77 Table 31. Evaluation of BBR 22 building envelope U mean requirements, of Linnea building with partly prefabricated exterior wall option 1. Nr. of Quantity Unit Sandwich Roof Slab- Window stories wall element construction on- grade 3 U i W/(m 2 K) A i m A om m U m W/(m 2 K) U i W/(m 2 K) A i m A om m U m W/(m 2 K) U i W/(m 2 K) A i m A om m U m W/(m 2 K) 0.35 Table 32. Evaluation of BBR 22 building envelope U mean requirements, of Linnea building with partly prefabricated exterior wall option 2. Nr. of stories Quantit y Unit Singleelement Roof construction Slabongrade Windo w wall 3 U i W/(m 2 K) A i m A om m U m W/(m 2 K) U i W/(m 2 K) A i m A om m U m W/(m 2 K) U i W/(m 2 K) A i m A om m U m W/(m 2 K)

78 Table 33. Evaluation of BBR 22 building envelope U mean requirements, of Frida building with partly prefabricated exterior wall option 1. Nr. of Quantity Unit Sandwich Roof Slab- Window stories wall element construction on- grade 3 U i W/(m 2 K) A i m A om m U m W/(m 2 K) U i W/(m 2 K) A i m A om m U m W/(m 2 K) U i W/(m 2 K) A i m A om m U m W/(m 2 K) 0.37 Table 34. Evaluation of BBR 22 building envelope U mean requirements, of Frida building with partly prefabricated exterior wall option 2. Nr. of Quantity Unit Singleelement Roof Slab- Window stories wall construction on- grade 3 U i W/(m 2 K) A i m A om m U m W/(m 2 K) U i W/(m 2 K) A i m A om m U m W/(m 2 K) U i W/(m 2 K) A i m A om m U m W/(m 2 K) 0.37 Results show compliance with the requirement of maximum mean U-value 0.40 W/(m 2 K) for the whole building envelope enclosure stated in BBR 22. Furthermore the material specific assembly requirements of ASHRAE for climate zone 5 are fulfilled. Roofs insulated entirely above deck is set to W/(m 2 K) compared to the calculated U-value of 0.12 W/(m 2 K) 69

79 Exterior walls of mass material is set to W/(m 2 K) compared to the calculated U-value of 0.18 W/(m 2 K) Unheated slab-on-grade floor of mass material is set to W/(m 2 K) compared to the calculated U-value of 0.12 W/(m 2 K) Vertical fenestration with nonmetal framing is set to 1.99 W/(m 2 K) compared to chosen fenestration and doors at U-value 1.05 W/(m 2 K) The average U-value of fenestrations found in the BETSI projects was found at 1.9 W/(m 2 K), these fulfill the ASHRAE requirements of vertical fenestrations. However the same U-value would increase the mean U-value of the envelope performance above 0.40 W/(m 2 K) for the same window-to-wall ratio. The windows used in multi-family dwellings during do not represent the thermal performance of windows today. 6.3 Analysis of LCA LCA for different building components In the following chapter the result of the LCA for different building components are presented. The analyses were carried out for 1 m 2 for each building component and the result is presented as emissions of kgco 2 -eqv/m 2 for each building component. The first bar in each case represents the starting point for each building component, which is presented in The used LCA data is presented in Appendix D. Figure 21 and Figure 22 present the distribution of each building elements effect to the total impact. This presents the effect each building components has on the total value. Concrete exterior walls, load-bearing inner walls and slabs stands for the majority of the total impact. These components regard the structural elements, which are constructed in concrete. The highest reduction was obtained when reducing the amount of cement in the concrete mixtures. This was done by varying the concrete qualities. 70

80 28% 5% 6% 5% 3% Building component distribution of total impact, Frida 6 stories External wall 2% 13% 38% Concrete inner walls Roof covering Joists Footing Slab-on-grade Roof construction Window and doors Figure 21. Pie chart presenting the distribution of each building component on the total impact for sandwich concrete element. Building component distribution of total impact, Linnea 6 stories 3% 5% 6% 4% 37% External wall Concrete inner walls Roof covering Joists Footing 27% 2% 16% Slab-on-grade Roof construction Window and doors Figure 22. Pie chart presenting the distribution of each building component on the total impact for sandwich concrete element. 71